Base class for handling audio devices. More...

#include <AsyncAudioDevice.h>

Inheritance diagram for Async::AudioDevice:

Public Types
enum	Mode { MODE_NONE , MODE_RD , MODE_WR , MODE_RDWR }
	The different modes to open a device in. More...

Public Member Functions
virtual size_t	readBlocksize (void)=0
	Find out what the read (recording) blocksize is set to.

virtual size_t	writeBlocksize (void)=0
	Find out what the write (playback) blocksize is set to.

virtual bool	isFullDuplexCapable (void)=0
	Check if the audio device has full duplex capability.

bool	open (Mode mode)
	Open the audio device.

void	close (void)
	Close the audio device.

Mode	mode (void) const
	Get the current operating mode of this audio device.

virtual void	audioToWriteAvailable (void)=0
	Tell the audio device handler that there are audio to be written in the buffer.

virtual void	flushSamples (void)=0

virtual int	samplesToWrite (void) const =0
	Find out how many samples there are in the output buffer.

int	sampleRate (void) const
	Return the sample rate.

const std::string &	devName (void) const
	Return the device name.

Static Public Member Functions
static AudioDevice *	registerAudioIO (const std::string &dev_designator, AudioIO *audio_io)
	Register an AudioIO object with the given device name.

static void	unregisterAudioIO (AudioIO *audio_io)
	Unregister a previously registered AudioIO object.

static void	setSampleRate (int rate)
	Set the sample rate used when doing future opens.

static void	setBlocksize (size_t size)
	Set the blocksize used when opening audio devices.

static void	setBlockCount (size_t count)
	Set the buffer count used when opening audio devices.

static void	setChannels (size_t channels)
	Set the number of channels used when doing future opens.

static size_t	getChannels (void)
	Get the number of channels used for future opens.

Protected Member Functions
	AudioDevice (const std::string &dev_name)
	Constuctor.

virtual	~AudioDevice (void)
	Destructor.

virtual bool	openDevice (Mode mode)=0
	Open the audio device.

virtual void	closeDevice (void)=0
	Close the audio device.

void	putBlocks (int16_t *buf, size_t frame_cnt)
	Write samples read from audio device to upper layers.

size_t	getBlocks (int16_t *buf, size_t block_cnt)
	Read samples from upper layers to write to audio device.

void	setDeviceError (void)
	Called by the device object to indicate an error condition.

Protected Attributes
std::string	dev_name

Static Protected Attributes
static int	sample_rate

static size_t	block_size_hint

static size_t	block_count_hint

static size_t	channels

Detailed Description

Base class for handling audio devices.

Author: Tobias Blomberg / SM0SVX

Date: 2004-03-20

This class implements a base class for supporting different audio devices. This class is not intended to be used by the end user of the Async library. It is used by the Async::AudioIO class, which is the Async API frontend for using audio in an application.

Definition at line 123 of file AsyncAudioDevice.h.

Member Enumeration Documentation

◆ Mode

enum Async::AudioDevice::Mode

The different modes to open a device in.

Enumerator
MODE_NONE	No mode. The same as close.
MODE_RD	Read.
MODE_WR	Write.
MODE_RDWR	Both read and write.

Definition at line 129 of file AsyncAudioDevice.h.

Constructor & Destructor Documentation

◆ AudioDevice()

Async::AudioDevice::AudioDevice ( const std::string & dev_name )

explicitprotected

Constuctor.

Parameters

dev_name The name of the device to associate this object with

◆ ~AudioDevice()

virtual Async::AudioDevice::~AudioDevice ( void )

protectedvirtual

Destructor.

Member Function Documentation

◆ audioToWriteAvailable()

virtual void Async::AudioDevice::audioToWriteAvailable ( void )

pure virtual

Tell the audio device handler that there are audio to be written in the buffer.

◆ close()

void Async::AudioDevice::close ( void )

Close the audio device.

◆ closeDevice()

virtual void Async::AudioDevice::closeDevice ( void )

protectedpure virtual

Close the audio device.

◆ devName()

const std::string & Async::AudioDevice::devName ( void ) const

inline

Return the device name.

Returns: Returns the device name

Definition at line 295 of file AsyncAudioDevice.h.

References dev_name.

◆ flushSamples()

virtual void Async::AudioDevice::flushSamples ( void )

pure virtual

◆ getBlocks()

size_t Async::AudioDevice::getBlocks	(	int16_t *	buf,
		size_t	block_cnt )

protected

Read samples from upper layers to write to audio device.

buf Buffer which will be filled with frames of samples

block_cnt The size of the buffer counted in blocks

Returns: The number of blocks actually stored in the buffer

This function is used by an audio device implementation to get samples from upper layers to write to the actual audio device. The count is given in blocks. The buffer must be able to store the number given in block_cnt. Fewer blocks may be returned if the requested block count is not available. The number of samples a block contain is ret_blocks * writeBlocksize() * channels.

◆ getChannels()

static size_t Async::AudioDevice::getChannels ( void )

inlinestatic

Get the number of channels used for future opens.

Returns: Returns the number of channels used for future opens

Definition at line 235 of file AsyncAudioDevice.h.

References channels.

◆ isFullDuplexCapable()

virtual bool Async::AudioDevice::isFullDuplexCapable ( void )

pure virtual

Check if the audio device has full duplex capability.

Returns: Returns true if the device has full duplex capability or else false

◆ mode()

Mode Async::AudioDevice::mode ( void ) const

inline

Get the current operating mode of this audio device.

Returns: Returns the current mode (See AudioIO::Mode)

Definition at line 260 of file AsyncAudioDevice.h.

◆ open()

bool Async::AudioDevice::open ( Mode mode )

Open the audio device.

Parameters

mode	The mode to open the audio device in (See AudioIO::Mode)

Returns: Returns true on success or else false

◆ openDevice()

virtual bool Async::AudioDevice::openDevice ( Mode mode )

protectedpure virtual

Open the audio device.

Parameters

mode	The mode to open the audio device in (See AudioIO::Mode)

Returns: Returns true on success or else false

◆ putBlocks()

void Async::AudioDevice::putBlocks	(	int16_t *	buf,
		size_t	frame_cnt )

protected

Write samples read from audio device to upper layers.

Parameters

buf	Buffer containing frames of samples to write
frame_cnt	The number of frames of samples in the buffer

This function is used by an audio device implementation to write audio samples recorded from the actual audio device to the upper software layers, for further processing. The number of samples is given as frames. A frame contains one sample per channel starting with channel 0. Frames are put in the buffer one after the other. Thus, the sample buffer should contain frame_cnt * channels samples.

◆ readBlocksize()

virtual size_t Async::AudioDevice::readBlocksize ( void )

pure virtual

Find out what the read (recording) blocksize is set to.

Returns: Returns the currently set blocksize in samples per channel

◆ registerAudioIO()

static AudioDevice * Async::AudioDevice::registerAudioIO	(	const std::string &	dev_designator,
		AudioIO *	audio_io )

static

Register an AudioIO object with the given device name.

Parameters

dev_designator	The name of the audio device
audio_io	A previously created AudioIO object

Returns: Returns an AudioDevice object associated with the given device

This function is used to register an AudioIO object with the given audio device. If an AudioDevice object already exist for the given device, it is returned. If there is no AudioDevice object for the given device, a new one is created.

◆ sampleRate()

int Async::AudioDevice::sampleRate ( void ) const

inline

Return the sample rate.

Returns: Returns the sample rate

Definition at line 289 of file AsyncAudioDevice.h.

References sample_rate.

◆ samplesToWrite()

virtual int Async::AudioDevice::samplesToWrite ( void ) const

pure virtual

Find out how many samples there are in the output buffer.

Returns: Returns the number of samples in the output buffer on success or -1 on failure.

This function can be used to find out how many samples there are in the output buffer at the moment. This can for example be used to find out how long it will take before the output buffer has been flushed.

◆ setBlockCount()

static void Async::AudioDevice::setBlockCount ( size_t count )

inlinestatic

Set the buffer count used when opening audio devices.

Parameters

count The buffer count to use

Returns: Returns the buffer count actually set

Use this function to set the buffer count used when opening audio devices. The buffer count is the maximum number of blocks the driver will buffer when reading and writing audio to/from the sound card. Lower numbers give less delay but could cause choppy audio if the computer is too slow. This is a global setting so all sound cards will be affected. Already opened sound cards will not be affected.

Definition at line 212 of file AsyncAudioDevice.h.

References block_count_hint.

◆ setBlocksize()

static void Async::AudioDevice::setBlocksize ( size_t size )

inlinestatic

Set the blocksize used when opening audio devices.

Parameters

size	The blocksize, in samples per channel, to use

Returns: Returns the blocksize actually set

Use this function to set the block size used when opening audio devices. The block size is the size of the blocks used when reading and writing audio to/from the sound card. Smaller blocks give less delay but could cause choppy audio if the computer is too slow. The blocksize is set as samples per channel. For example, a blocksize of 256 samples at 8kHz sample rate will give a delay of 256/8000 = 32ms. This is a global setting so all sound cards will be affected. Already opened sound cards will not be affected.

Definition at line 182 of file AsyncAudioDevice.h.

References block_size_hint.

◆ setChannels()

static void Async::AudioDevice::setChannels ( size_t channels )

inlinestatic

Set the number of channels used when doing future opens.

Parameters

channels The number of channels to use

Use this function to set the number of channels used when opening audio devices. This is a global setting so all sound cards will be affected. Already opened sound cards will not be affected.

Definition at line 226 of file AsyncAudioDevice.h.

References channels.

◆ setDeviceError()

void Async::AudioDevice::setDeviceError ( void )

protected

Called by the device object to indicate an error condition.

◆ setSampleRate()

static void Async::AudioDevice::setSampleRate ( int rate )

inlinestatic

Set the sample rate used when doing future opens.

Parameters

rate	The sampling rate to use

Use this function to set the sample rate used when opening audio devices. This is a global setting so all sound cards will be affected. Already opened sound cards will not be affected.

Definition at line 166 of file AsyncAudioDevice.h.

References sample_rate.

◆ unregisterAudioIO()

static void Async::AudioDevice::unregisterAudioIO ( AudioIO * audio_io )

static

Unregister a previously registered AudioIO object.

Parameters

audio_io A previously registered AudioIO object

◆ writeBlocksize()

virtual size_t Async::AudioDevice::writeBlocksize ( void )

pure virtual

Find out what the write (playback) blocksize is set to.

Returns: Returns the currently set blocksize in samples per channel

Member Data Documentation

◆ block_count_hint

size_t Async::AudioDevice::block_count_hint

staticprotected

Definition at line 301 of file AsyncAudioDevice.h.

Referenced by setBlockCount().

◆ block_size_hint

size_t Async::AudioDevice::block_size_hint

staticprotected

Definition at line 300 of file AsyncAudioDevice.h.

Referenced by setBlocksize().

◆ channels

size_t Async::AudioDevice::channels

staticprotected

Definition at line 302 of file AsyncAudioDevice.h.

Referenced by getChannels(), and setChannels().

◆ dev_name

std::string Async::AudioDevice::dev_name

protected

Definition at line 304 of file AsyncAudioDevice.h.

Referenced by devName().

◆ sample_rate

int Async::AudioDevice::sample_rate

staticprotected

Definition at line 299 of file AsyncAudioDevice.h.

Referenced by sampleRate(), and setSampleRate().

The documentation for this class was generated from the following file:

AsyncAudioDevice.h

Public Types

Public Member Functions

Static Public Member Functions

Protected Member Functions

Protected Attributes

Static Protected Attributes

Detailed Description

Member Enumeration Documentation

◆ Mode

Constructor & Destructor Documentation

◆ AudioDevice()

◆ ~AudioDevice()

Member Function Documentation

◆ audioToWriteAvailable()

◆ close()

◆ closeDevice()

◆ devName()

◆ flushSamples()

◆ getBlocks()

◆ getChannels()

◆ isFullDuplexCapable()

◆ mode()

◆ open()

◆ openDevice()

◆ putBlocks()

◆ readBlocksize()

◆ registerAudioIO()

◆ sampleRate()

◆ samplesToWrite()

◆ setBlockCount()

◆ setBlocksize()

◆ setChannels()

◆ setDeviceError()

◆ setSampleRate()

◆ unregisterAudioIO()

◆ writeBlocksize()

Member Data Documentation

◆ block_count_hint

◆ block_size_hint

◆ channels

◆ dev_name

◆ sample_rate